The durability of recycled concrete must be determined before this material can be used in construction. In this paper the alkali-silica reaction in recycled concrete is analyzed. The recycled concrete is made with recycled aggregates, composed by original limestone aggregates and adhered mortar with reactive silica sand, and high alkali content cement. Due to the manufacturing process used for concrete production and the high water absorption capacity of recycled aggregates, cement accumulation happens in the interface (ITZ). The concentration of alkalis on the surface of recycled aggregates- ITZ and the presence of reactive sand in the mortar adhering to the recycled aggregate induce an alkali-silica reaction in 6-month concrete. The existence of this reaction is confirmed by environmental scanning electron microscopy (ESEM) and EDX analysis. The mechanical properties of 6-month recycled concrete were similar to those values at 28-days of curing.

A new method for proportioning recycled aggregates concrete (RAC) is used to check its feasibility under the Spanish context. First, an extensive experimental campaign has been done, with the purpose of check and analyze the applicability of the EMV method with two Spanish recycled concrete aggregates (RCA). The aim of the second part of the investigation, was to elaborate an adaptation of the EMV method to Bolomey methodology (1), using a 20% weight replacement of coarse natural aggregates (NA) for RCA, and so, with this, comply with the Spanish Instruction for Structural Concrete (EHE 2008). Slump, air content, fresh and hardened densities, compressive strength and modulus of elasticity were determined and analyzed, in order to check the concrete properties. Finally, it was observed that, the EMV method is viable, and its adaptation, results in concrete mixes with similar or better properties than the natural aggregate concrete and RAC conventionally prepared.

Some durability properties are analyzed in concretes made with a novel method for recycled aggregates concrete (RAC) proportioning, in order to validate it under the Spanish context. Two types of concrete mixes were elaborated; one following the guidelines of the named method, and other based on an adaptation of the method to Bolomey methodology. Two types of recycled concrete aggregates (RCA) were used. RCA replacement for natural aggregates (NA) ranged from 20% to 100%. The 20% was chosen in order to comply with Spanish recommendations. Water penetration under pressure, water absorption and chlorides attack were the studied properties. It is verified that the new method and the developed adaptation results in concrete mixes of better or similar properties to those of the natural aggregates concrete (NAC) and the conventional RAC, saving important amounts of cement.

The structural health monitoring of historic buildings represents one of the most significant challenges in contemporary structural analysis, particularly for large-scale structures with accumulated damage. Obtaining reliable diagnostics is crucial yet complex due to the inherent uncertainties in both geometric definition and material properties of historic constructions, especially when structural stability may be compromised. This study presents a comprehensive structural assessment of the Bullring of the Real Maestranza de Caballería de Ronda (Spain), an emblematic 18th-century structure, through an innovative multi-technique approach aimed at evaluating its structural stability. The methodology integrates various non-destructive techniques: 3D laser scanning for precise geometric documentation, operational modal analysis (OMA) for global dynamic characterisation, experimental modal analysis (EMA) for local assessment of critical structural elements, and sonic tests (ST) to determine the elastic moduli of the principal materials that define the historic construction. The research particularly focuses on the inner ring of sandstone columns, identified as the most vulnerable structural component through initial dynamic testing. A detailed finite-element (FE) model was developed based on high-precision laser-scanning data and calibrated using experimental dynamic properties. The model’s reliability was validated through the correlation between numerical predictions and experimental observations, enabling a thorough stability analysis of the structure. Results reveal concerning stability issues in specific columns of the inner ring, identifying elements at significant risk of collapse. This finding demonstrates the effectiveness of the proposed methodology in detecting critical structural vulnerabilities in historic buildings, providing crucial information for preservation strategies.